Mail to nowhere

[Richard]

> Date: Tuesday, June 16, 2015 07:21:06 PM -0400
> From: Steve Matzura <number6 at noisynotes.com>
>
> On Tue, 16 Jun 2015 22:02:29 +0200, you wrote:
> 
>> Am Dienstag, den 16.06.2015, 11:44 -0400 schrieb Steve Matzura:
>>> The next phase of my testing procedure involves the simple act of
>>> delivering mail to my test box. When I send a message to either a
>>> valid or relayed user at my remote machine's address, it never
>>> gets there. I know this virtually for sure because I'm tailing
>>> /var/log/maillog and nothing new has been added for the past
>>> hour.  I'm
>>> thinking eventually my ISP will send the message back to me as
>>> undeliverable, and in that bounced message there may be some
>>> information about why it was undeliverable, but maybe someone
>>> has a thought as to why I'm not even seeing anything attempt to
>>> connect?
>> 
>> Receiving and Sending Mail is done by the MTA like postfix or
>> exim. Not Dovecot. It's just for the IMAP/POP access by the users
>> to get the mails.
>> So look at that logs. And if there's nothing in it, then make
>> sure port 25 is actually open by the postfix/exim process.
> 
> Well, it isn't. In fact, there is no exim process running. However,
> something calling itself 'master' has port 25 open according to
> netstat, and that process has a subprocess running something called
> qmgr. I'd give more information, such as path to these programs,
> but it isn't shown.
> Time to check my Postfix config a little more closely.

Those pieces are all part of the postfix MTA (you haven't indicated
your OS, but postfix is the current default on most current linux
distributions).

As I indicated earlier, by default most (current) MTA installs only
listen on localhost, not on the external interfaces, so don't accept
off-host mail.

There is extensive postfix documentation and also a postfix mailing
list if you need assistance.